I'm not completely sold on Jeffers, but I will give him the benefit of a doubt, when it comes to his hitting. There are several catchers who struggled offensively early in their careers. Some of them became decent hitters.
I think the young man is really trying to establish himself as a catcher, first. Learning his staff, opposing hitters and runners are more of a priority for him, right now. In fact, with this team, he may be mandated to concentrate on his defensive, and any offense he generates is great, for now. A Twins lineup of lesser ability would require a larger offensive contribution.